1. Filed of the Invention
The present invention a polypropylene resin composition having excellent thermal aging resistance, weatherability and antistatic property, wherein the amount of components vaporized from the resin (referred to as "thermal vaporization property") is small when used at high temperature.
2. Prior Art
A polypropylene resin is widely used for a molded article, film, fiber and the like because of its excellent mechanical properties and easy processability, however, has defects that since it is an electric insulator, once charged static electricity does not easily flow off and consequently trash and dust tend to adhere to the surface of a product, in addition to degradation easily caused by the action of heat and light (mainly, ultraviolet ray).
To solve the defects, it is known to add a phenol-based antioxidant, phosphorus-based antioxidant, sulfur-based antioxidant or the like, alone or in combination to polypropylene, for preventing degradation due to heat, and to add a salicylate, benzophenone-based compound, benzotriazole-based compound, hindered amine-based compound and the like as a weather resistant stabilizer, alone or in combination to polypropylene, for preventing degradation due to a light, and in addition, it is also known to optionally use antistatic agents such as an alkyldiethanolamine, fatty acid diethanolamide, glycerin monofatty acid ester and the like, alone or in combination thereof.
With recent expansion of use of polypropylene, it is often practiced to add an antistatic agent so that trash and dust do not easily adhere to the surface of a molded article, in addition to the addition of a synthetic rubber, inorganic filler, pigment and the like for improving mechanical properties thereof and ability, appearance and the like of the molded article. Further, requirements regarding thermal resistance and weatherability have been increasing, and a compounding which is intended to be used under higher temperature than ever is required.
However, it is clear that a molded article made of a composition in which these antioxidant, weather resistant agent and antistatic agent are compounded causes various problems that sufficient result can not be obtained by complicated interaction of the additives in a polypropylene, and further, that tone deteriorates, environmental pollution occurs due to vaporization of a part of the additives when used at high temperature.